Vacuum-Cast Into RTV vs Degassing Rubber | RUUIPON

Vacuum-casting means you pull air on *the dump* — resin, PU, or a wax — while it sits in or flows into a finished platinum mold. Degassing mixed RTV means you pull air on *the rubber* in a cup before it ever sees the master. Same physics, different step, usually different chamber, different leak rules. Using the rubber-degas SOP on a thin UV resin will cook pot life. Using a casting vacuum on an unsealed mold box while you pour the *skin* can suck air in through the dams. Food cavities are not vacuum-cast: chocolate and gummy dumps stay atmospheric, dry, no grease, no tin.

RUUIPON vacuum-degases platinum A/B for the tool in Bao'an since 2018. Prototype 3–7 business days after CAD lock. MOQ 20 pieces per design. USD $50 when CAD scope applies. [email protected] · +86 135 3006 2969. LSR *parts*: wydsilicone.com.

Does not apply when you meant a pressure pot on the dump, when you are running LSR in a heated cavity with a cold-runner, or when the "vacuum" is a cheap bag around a leaking flask. Don't paste 177.2600 onto a vac-cast PU.

Two chambers, two leak paths

Chamber A — mixed platinum, cup with headspace. Pull until foam rises and collapses. This is how we keep pinholes off a chocolate serif and a clear resin face. Brush/detail coats still wet verticals; vacuum does not replace a stipple.

Chamber B — finished mold plus dump. You either degas the resin in a cup then pour, or you fill under vacuum (true vacuum-cast). The mold must not collapse. Soft 10A–20A gloves need a jacket. Open-back trays need a path that doesn't suck the dump through a vent you didn't plan.

Leaks: a hot-glue dam that held for a gravity pour will whistle under vacuum and seed bubbles along the seam — in the dump, not in the already-cured rubber. Production flasks and keyed jackets exist for that reason.

If the empty well is already cratered, vacuum on the dump cannot invent a smooth face. Recast the skin.

Thin UV resins foam and then gel while you wait for the gauge. Don't copy a platinum collapse time onto that cup.

Food stays out of chamber B

Chocolate, gummy, ice, baking, popsicle: we pull vacuum on the *rubber* that makes the tray, then you dump at atmosphere. We would not vac-cast couverture. We would not grease a well "so vacuum works." We would not spec tin because a jewelry video used a chamber. A well that saw PU under vacuum is retired from food.

ISO 3302-1 M2 is a drawing class on the dump, not a millibar spec. Don't write M2 as a substitute for a leak-tight jacket.

flowchart TD
  A[Vacuum somewhere] --> B{Which material is still liquid?}
  B -->|mixed RTV going onto master| C[Chamber A: degas the rubber]
  B -->|resin going into finished mold| D[Chamber B: vacuum-cast the dump]
  D --> E{Food dump?}
  E -->|yes| F[Stop — atmospheric food, dry well, no tin]
  E -->|no craft| G{Skin jacketed and flask leak-tight?}
  G -->|no| H[Fix the tool / jacket first]
  G -->|yes| I[Named vacuum-cast cycle for that resin]
  C --> J[Then pour or brush the skin]

The photo that would prove the split: cup of foaming platinum in chamber A, versus a closed mold in chamber B with a catch-pot, both labeled. One glamour shot of a bubble-free dice is not the proof.

Typical shop values

Caption: Typical shop values.

Collapse time is not a millibar brag

Platinum foam-collapse is a visual: rise, break, settle, short hold. Jewelry UV and thin epoxy don't get that luxury. Pulling until the gauge "looks like the RTV video" is how you gel a dump in the cup and then blame the mold. Write the resin family and the intended vacuum-cast dwell on the RFQ. We will say if the glove and jacket can live through it.

A second leak path people miss: porous SLS or unsealed plaster jackets breathe under vacuum and seed a fog of microbubbles on the dump face while the rubber well stays glossy. Seal or change the mother; don't add ten minutes of vacuum.

Worked example (anonymized)

Two-part figurine, platinum ~20A, FRP jacket. Buyer vacuum-cast PU; bubbles along the parting. Rubber face was glossy — leak at a hot-glue repair on the jacket, not a degas skip on our pour. We rebuilt the jacket seam, kept the skin, no $50 CAD. Next vac-cast was clean. MOQ 20 skins already shipped. We did not "add more vacuum time" to a leaking mother.

One procurement mix-up

One chamber on the PO as if it serves both steps. Ask which material is liquid in the chamber. Tooling charge is not a vacuum pump, and it is not unrestricted ownership if you collapse a glove that we said needed a jacket.

We would not recommend

We would not recommend vacuum-casting chocolate, gummy, or ice.

We would not recommend copying platinum foam-collapse time onto UV resin.

We would not recommend vac-casting a jacketless 10A glove.

We would not recommend using vacuum to hide a cratered cavity face.

What to ask when you're buying

• Chamber for rubber, for dump, or do you own two cycles?
• Resin family and pot life under vacuum?
• Jacket that won't leak or crush?
• Open-back vents — planned, or a whistle?
• Food vs craft — stay split?

RFQ copy-pack

Send to [email protected] · +86 135 3006 2969 · Xinhe Blvd, Shajing, Bao'an.

RUUIPON vacuum-cast dump RFQ Dump: PU / epoxy / UV / wax / food (food = no vac-cast) Rubber already degassed at pour? yes / no Jacket: FRP / printed / plaster / none Leak history: seam bubbles / face craters / none Qty: witness / MOQ 20 CAD: locked / $50 3D if vents or split must change

Matched next step: say which material is liquid in the chamber. We degas rubber on the tool; we jacket skins that will live under dump vacuum. We will not vac-cast food. Prototype 3–7 business days after CAD lock. MOQ 20 per design.

Related: pressure pot vs vacuum, how long to vacuum degas RTV, custom figurine molds, contact.

FAQ

Can one chamber do rubber degas in the morning and PU vac-cast in the afternoon? If it is rated, clean, and you don't contaminate food tools in the same cabinet. Still two recipes. Don't leave PU film in a chamber you later use on a platinum cup for a chocolate tray.

Why did vacuum make more bubbles in my UV resin? You pulled on a mix that foamed past pot life. Shorter cycle or a different resin. Don't copy our RTV collapse SOP.

Do food trays get vacuum on the rubber, the dump, or both? On the rubber, in the cup, before the pour. The chocolate dump stays at atmosphere. Dry well.

Will vacuum-casting replace a split on a hooked figurine? No. Vacuum does not open an undercut. Structure Decision first.

If the jacket leaks, do I recast the skin? Usually no. Fix the mother. Recast the skin if the face is already cratered or torn. CAD fee only if vents or splits must move.